Dental drilling instrument



Aug. 24, 1937. H. CLARK DENTAL DRILLING INSTRUMENT Filed April l2, 1955 Patented Aug. Z4, 1937 UNITED STATES PATENT oFFlcE 6 Claims.

This invention relates to improvements in dental drilling instruments, and a principal object of the invention is to provide a novel construction facilitating replacement of the operating parts when such replacement becomes necessary by reason of excessive wear.

Dental drills are necessarily precision instruments and must be manufactured to relatively close tolerances. The instruments also by reason of their relatively high operating speeds are subject to Wear, which interferes with the precise operation required in tools of this character. Heretofore the instruments have been so constructed that the repairs required to maintain them in efficient operating condition involved diflicult and time-consuming operations beyond the capacities of the average practitioner and reconditioning was, therefore, a factory operation involving a considerable expense and loss of time.

An object of the present invention, therefore, is to provide a construction making possible immediate repair of worn instruments by the practitioner, and to thereby avoid the undue expense "g5 and delay attending such repairs on instruments of the prior construction.

More specifically the invention contemplates the provision in an instrument of this character of a unit mechanism including the rotary chuck in which the burr is detachably inserted together with the bearings for said chuck, with provision for detachably mounting this unit in proper position within the casing of the instrument, and the invention further resides in the novel mechanical and structural details and elements by means of which this end is attained.

In the attached drawing:

Figure 1 is a side and partial sectional view of an instrument made in accordance with my invention;

Fig. 2 is an enlarged fragmentary sectional view of the head end of the instrument;

Figs. 3, 4 and 5 are views in perspective of elements of the casing or housing, and

Fig. 6 is a view in perspective of the unit mechanism constituting the essential novel feature of the invention.

With reference to the drawing, an instrument embodying my invention may comprise the usual hollow shank I vwhich houses the operating elements of the drill and which in the present instance comprises two separable parts 2 yand 3 meeting on a longitudinal dividing line 4. The parts 2 and 3, as shown in Figs. 3 and 4; have abutting flat surfaces and are held together by means of a sleeve 5 which embraces and receives the threaded extremities 2a and 3a.4 of the parts. By means of the threads, the beveled shoulder 6 60 of the shank I is drawn firmly down upon a cor- 4respondingly formed seat 'I in one end of the sleeve 5. q

As shown in Fig. 2, the shank I is provided with a longitudinal bore 8 which receives and constitutes a journal for a shaft 9 which projects meshes with a pinion I3, this pinion in the pres-A ent instance being shown as an integral part of a sleeve I4 mounted for rotation in the head end I5 of the shank I. The sleeve I4 is journaled in a bearing comprising telescoping parts I5 and I'I, which bearing as shown in Figs. 2 and 6 embraces the sleeve and is cut away at one side to expose the pinion I3 for engagement with the pinion I2` and to provide the recess required for lreception of the latter pinion.

In assembly, the flat face I8 of the cut-out portion of the bearings I6 and II lies flush against a corresponding flat surface I9 on the inside of the shank element 3, see Fig. 4, whereby the elements I6 and I'I are held against rotational movement within the shank. The reduced extremity 2| of the bearing element I6 is threaded, and in assembly is received by the internally threaded head end of the shank element 2, and in accordance with' my invention, the bearing elements I6 and II are secured together either by welding or soldering, as indicated at 22, or in -any other suitable manner. It will be apparent, therefore, that the sleeve I4 with its pinion I3 and the bearing elements I6 and I1 constitute a unit which may be inserted and detached from the shank I at will and which when inserted in the shank is Afirmly secured and positively positioned within the latter.

In assembling the instrument, the sleeve 5 is unthreaded from the shank I, thereby permitting separation of the elements 2 and 3. The unitarymechanism consisting of the sleeve I4, pinion I3 and bearing elements I6 and I1 is then threaded into the shank element 2, these parts being so relatively formed that when the shoulder 23 of the element I6 is firmly engaged with the abutting shoulder of the element 2, the face I8 will extend at right angles to the axis of the bore 8. The shank element 3 by reason of, the face I9, which as previously set forth engages the face I8 of the unit mechanism, is adapted to be used as a wrench to adjust the unit into an accurately aligned position. It is now possible to insert the shaft 9 so that its pinion I2 meshes with the pinion I3, after which the shank element v3 is brought together with the element 2 and assembled with the sleeve 5 as previously described. It will be noted that the shaft 9 bore of the sleeve I4 and being provided adjacentv4 its inner end with a flat 26 which in assembly engages a corresponding flat surface 2l in thev sleeve I4 whereby the burr is fixed, rotatably,` to the sleeve. In accordance with the usual practice, the end of the shank of the burr 25 is provided .with a circumferential groove 28 which receives the hooked end of. a clip 29 adjustably secured to the shank element 3, as best shown in Fig. 5, this clip functioning to clamp the burr 25 against axial movement within the chuck I4. In the present instance, the clip 29 is pivotally mounted at 3| within a slotted recess 32 in the shank element 3, and the resilient tool end 33 of the clip is provided with a ball-like projection 3d which when the clip is in the burr-retaining position engages in the outer end of a port in the shank to thereby retain the clip securely in its operative position. The projection 34 also functions to close the outer end of the port 35 which is adapted to function as a passage for admission of a lubricant to the journal 8 of the shaft 9. y

It will be noted that in the aforedescribed construction all of the rotating or working parts of the mechanism are readily ldetachable from the casing or housing, and are so formed as to be readily replaceable by new parts whenrequired. If by reason of wear either in the rotary chuck element I4 or in the journal elements IB and Il an excessive amount of. play develops in these working parts, it is only necessary for the practitioner to separate the shank el-ements 2 and 3, remove the shaft 9 with its pinion I2, and to then release the unit mechanism consisting of the other working parts by unscrewing the unit from the shank element 2. 'I'his may readily be accomplished by utilizing the shank element 3, as previously described, as a Wrench. The unit mechanism may then be replaced by new mechanism of the same construction and the instrument re-assembled for immediate use. This operation being well within the capacity of the practitioner himself, all the delays and a substantial proportion of thev expense heretofore involved in such repairs are avoided. It will be apparent also that the construction facilitates maintenance of the instrument in clean, sanitary and well lubricated condition.

It will be understood that the invention is capable of other embodiments than that illustrated.

I claim:

1. In a dental instrument of the character described, the combination with a casing, of operating mechanism comprising a drive shaft journaled in the casing, a rotary chuck, a bearing for d the chuck constituting the sole chuck-supporting means, and means for operatively connecting the chuck to the shaft; said casing being formed iriteriorly with a seat for said bearing in which said bearing is held detachably in fixed predetermined position with respect to said shaft, and said chuck and bearing being formed as a unit, and as such being insertible in and detachable from the casing.

2. In a dental instrument of the character de- Awith the said drive gear; said casing and bearing being formed with complementary surfaces affordirig the latter a seat within the casing, and.

. said mechanism being insertible in and detachable from the casing as a unit.

3. 'Ina dental instrument of the character described, the combination with a casing having a longitudinal bore, and la socket extending at an angle tolsaidboravof a drive shaft journaled in the bore 'and having a pinion extending into said socket;A and a unit mechanism comprising a rotary chuck; a bearing non-rotatably and detachablyseated in said socket and constituting the sole supporting journal for said chuck; and a pinion'carried by the chuck andV meshing with said drive pinion, said'casing and bearing being formed with complementarysurfaces affording the latter a seat within the casing, and said mechanism being insertable in and detachable from said casing as a unit.

4. In a dental instrument of the character described, the combination with a casing having longitudinallyv separable sections and means for securing said sections together, said sections having registering recesses at one end forming a transverse socket, a longitudinal drive shaft journaled between said sections and having a pinion extending into `said socket, and a unit mechanism seating in said socket and comprising a bearing member threaded into the recess of one lof lsaid sections, a rotary chuck journaled in'said bearing member, and a gear carried by said chuck and meshing with said drive gear, said drive shaft and the unit mechanism being detachable from the casing by separation of said `casing sections.

5. In' a dental instrument of the character described the combination with a casing having longitudinally separable sections and means for securing said sections together, said sections having registeringrecesses at one end forming a transverse socket, a longitudinal drive shaft journaled between said sections and having a pinion extending into said socket, and a unit mechanism seating in said socket land comprising a bearing member threaded into the recess of one of said sections and having a non-rotatable releasable connection with the other section, a rotary chuck journaled in said bearing member, and a gear carried by said chuck and meshing with said drive gear, said drive shaft and theA unit mechanism being detachable from the casing by separation of said casing sections.

6. In a`- dental instrument of the character described, the combination with a casing, of operating mechanism comprising a drive shaft journaled in the casing, a rotary tool chuck, a bearing for the chuck, and means for operatively connecting 

